Jump pads are in the SFX
texture category. Pads are 128x128. Make a pad with the matching floor
texture and make it level with the floor, then choose carve. (This will
make the pad look like it is on the floor, when its actually a completely
different brush as the floor.) Now make a new brush that is about 16 units
high off of the jump pad that also covers it, and go to common
textures and choose trigger. Right click and choose trigger/
trigger_push for the new brush that is sitting on top of the jump pad.
Deselect it by pushing Esc and above it choose right click it and choose
target/target_position. Then press n to bring up the Entity window and for
key type in targetname and in the value type a name like 01jump.
(This gives the entity a name) Target_position is selected in the upper
box this tells you what entity is being edited. (Ignore the Origin, that's
the position of the entity). This entity (the target_position) tells the
"trigger box" what direction, and how high the jump should be.
It tells the trigger box this, by it's position. Now we need to bind the
trigger box to the target_position entity. That's why we put a targetname
on the entity. Now push ESC to deselect the target_position entity, and
select the brush with the trigger texture. Once you've selected it, push
N, to bring up the Entity window. Now simply type in the Key box target
and in the value 01jump or whatever you named the target_position.
(if you had the targetname MACsux on the entity, then you simply
put the value MACsux here). Now, there should be a line from the
trigger-box, to the entity. This line simply shows the direction of the
jump, and the player will reaches the highest point where the
trigger_position is. To get the player up to the right place, simply move
around the trigger_position entity.

Remember if you do not want to
have a jump pad texture you do not need one. All you need are these
things.

A brush with the trigger texture.

Right click and choose trigger/trigger_push for the
brush while it is selected.

push Esc to deselect everything then right click and
choose target/target_position.

push N to bring up the entity window for the
target_position.

for key type in targetname and for value type in a
name like 01jump.

push esc to deselt everything and select the brush
with the trigger texture.

push N and the fo key type in target and in the value
type the name of the target_position.

now there should be a line with arrows on it going
from the trigger_push to the target_position.